Clashes erupted at the presidential palace on Wednesday between supporters of President Mohamed Morsi and his opponents, the latter of whom have been protesting since Tuesday.
According to media statements, there is no security presence at the palace.
Private-owned television channel Al-Nahar reported that Islamist protesters were attacking tents belonging to anti-Morsi protesters.
The station also reported that activist Nawara Negm had been attacked by supporters of the president.
On Tuesday, hundreds of thousands marched to the palace to denounce Morsi's declaration and what they described as an "unrepresentative constitution."
The Muslim Brotherhood, meanwhile, has called on supporters to head to the palace on Wednesday to "protect the legitimacy" of the president.
The Islamist group has released a joint statement along with nine other Islamist groups accusing anti-Morsi protesters of carrying out acts of vandalism.